for more than 20 years /proc/uptime was good enough. I don't care about the boottime, but uptime certainly does not include the time the machine was suspended, so /proc/uptime is a reliable source of -- uptime! :-) Worked around for now with "ln -s /usr/bin/busybox /usr/local/bin/uptime", as /usr/local/bin fortunately is in $PATH before /usr/bin and busybox uptime works just fine.